[talk] Why do directories not contain data?

[Thomas Levine]

In every system I have used (not very many systems), if I write(2) to a
directory and read(2) from it, I either get errors or an empty result;
why are these calls not supported for directories?

The directory of course contains references to its children, but that's
not the information I'm thinking about accessing; I naively think that a
directory should be able to contain both a list of children (that I can
display with ls) and an arbitrary blob of unrelated data (that I can
display with cat); why I have never seen a system that works like this?